1. Field of the Invention
The invention applies generally to a method for selecting a bearer service for communication between a mobile terminal and a mobile network, in which method at least one bearer service is implemented in the mobile network. The invention also applies to a communication system which comprises at least a mobile terminal, a mobile network, at least one bearer service implemented in the mobile network, and means for selecting a bearer service for communication between said mobile terminal and said mobile network. The invention further applies to a mobile terminal for use in a communication system which comprises at least a mobile network, at least one bearer service implemented in the mobile network, and means for selecting a bearer service for communication between said mobile terminal and said mobile network.
2. Brief Description of Related Developments
The term “mobile communication system” refers generally to any communication system which enables a wireless communication connection between a mobile station (MS) and the fixed parts of the system when the user of the mobile station is moving within the service area of the system. A typical mobile communications system is the public land mobile network (PLMN). The majority of mobile communication systems in use at the time of filing this patent application belong to the second generation of such systems, a well-known example being the GSM system (Global System for Mobile Telecommunications). The invention applies advantageously to the next or third generation of mobile communication systems. The general packet radio service GPRS, a new service under development for the GSM mobile communication system and the 3rd generation Universal Mobile Telecommunications System, which is currently undergoing standardization, will be used as examples.
The functional environment of the GPRS system comprises one or more subnetwork service areas, which are connected to form a GPRS backbone network. The subnetwork comprises numerous support nodes (SN), of which serving GPRS support nodes (SGSN) will be used as an example in this specification. The serving GPRS support nodes are connected to the mobile communication network (typically to a base station via an interface unit) in such a way that they can provide packet switching services for wireless communication devices via base stations (cells). The mobile communication network provides packet-switched data transmission between the support node and the wireless communication device. Different subnetworks may be, in turn, connected to external data networks, for example to a public switched data network (PSDN), via GPRS gateway support nodes (GGSN). Thus, the GPRS service enables packet-format data transmission between a wireless communication device and an external data network, wherein certain parts of the mobile communication network form an access network. Some examples of applications utilising packet-format data transmission are Internet telephony, video conferencing, file transfer and WWW browsing.
In third-generation systems, the concepts of a bearer service and a service are used. A bearer service is a type of telecommunication service that provides the capability for the transmission of signals between access points. A bearer service generally corresponds to the older concept of a traffic channel, defining for example the use of data rate and quality of service (QoS) that will be provided by the system for transferring information between a mobile station and some other part of the system. For example, a bearer service between the mobile station and a base station is a radio bearer service, and a bearer service between a radio network controller and a core network is e.g. an lu bearer service (Interface UMTS bearer). In the UMTS system the interface between a radio network controller and a core network is called the lu interface. In this context a service is provided by a mobile communication network in order to fulfil some task(s), e.g. data services carry out data transfer in the communication system, call services are associated with phone calls, multimedia, etc. Therefore a service necessitates information transfer between a mobile station and the fixed parts of the system, like a phone call or the transfer of a text message. A major task in the operation of a third-generation mobile telecommunications system is to manage (set up, maintain and terminate, as necessary) the bearer services so that each requested service can be provided to mobile stations without wasting the available bandwidth.
The quality of service level defines, for instance, how packet data units (PDU) are handled in the GPRS network during transmission. For example, the quality of service levels defined for the connection addresses are used to control the order of transmission, buffering (packet queues) and discarding of packets in support nodes and in gateway support nodes, especially when there are two or more connections which have packets to be transmitted simultaneously. Different quality of service levels define, for example, different delays for packet transmissions between different ends of the connection, as well as different bit rates. The number of discarded packet data units can also vary in connections having different quality of service levels.
For each connection, it is possible to request a different quality of service level. For example in e-mail connections, a relatively long delay can be allowed in the message transmission. However, interactive applications, such as video conferencing for example, require high-speed packet transmission. In some applications, as in file transfer, it is important that the packet transmission is error free, wherein packet data units are re-transmitted in error situations, if necessary.
It has been suggested that four different traffic classes be defined in the packet transmission service of the UMTS system, and as for the features of these traffic classes, the aim has been to take into account the different criteria for the different connection types. One criterion defined for the first and the second class is the real-time quality of the data transmission, wherein significant delays must not occur in the transmission. However, the accuracy of the data transmission is not such an important criterion. Correspondingly, for the third and fourth traffic classes, non-real-time data transmission is sufficient, but relatively accurate packet transmission is required. An example of real-time first-class data transmission is the transmission of speech signals in a situation where two or more people discuss with each other via wireless communication devices. An example of a situation where real-time second-class data transmission could be possible, is the transmission of a video signal for immediate viewing. Third-class, non-real-time packet communication can be utilised for example for the use of database services, such as browsing Internet home pages, in which data transmission with moderate speed and accuracy is a more important factor than real-time data transmission. In the fourth class of this example system, it is possible to categorise for instance the transfer of e-mail messages and files. It is obviously not necessary to have four said traffic classes, but the invention can be applied in packet transmission systems containing any number of traffic classes. Further, the present invention can also be applied in circuit switched systems. The properties of the four proposed traffic classes are summarized in table 1.
TABLE 1ClassFirst class: real-time, e.g.Second class (business class):Third class (tourist class):Fourth class (cargo class):telephone conversationreal-time, e.g. video informationinteractive best effort methodbackground transmission with bestguaranteed capacityguaranteed capacityacknowledgementeffort methodno acknowledgementacknowledgement possibleInternet browser, Telnetacknowledgementbuffering on application levelreal-time control channelbackground download of e-mailmessages, calendar events, etc.Delay100 ms, 200 ms, 300 ms<1 s2 sNot definedBit error rate10−3, 10−4, 10−5, 10−610−5, 10−6, 10−7, 10−9<10−9<10−9Max bit rateDefinedDefinedNot definedNot definedUser priorityHigh, medium, lowHigh, medium, lowHigh, medium, lowHigh, medium, low
Modern second and third generation mobile stations have much more efficient data processing properties than older mobile stations. There is already, for example, a possibility to make a connection to the Internet and to use a browser application in the mobile station to obtain information from the Internet, and in future it will be possible to establish multimedia calls with e.g. real-time video conferencing and the like. Therefore, such mobile stations will be designated as mobile terminals hence forward in this description. The term mobile terminal should also be understood to include so-called “radio cards” which comprise mobile telephone circuitry integrated into a circuit card. Such radio cards can be removably connected, for example via a PCMCIA interface, to data processing devices, such as portable or laptop computers, in order to provide mobile telephone functionality or data transfer capability via a radio communication network.
To allow the use of different applications in such a mobile terminal, there will be provided an execution environment for external applications, hereafter abbreviated as execution environment in this description. Such external applications are not necessarily provided only by the manufacturer of the mobile terminal but some third party manufacturers may also provide such applications. To assure compatibility between mobile terminals and external applications, the mobile application execution environment (MExE) standard is under development. The present invention is not restricted to the mobile application execution environment standard but it can also be applied with other suitable execution environments for mobile terminals.
The user of a mobile terminal can have access to many kinds of service via a mobile telecommunication network using the mobile terminal. There is an enormous number of service providers connected to e.g. the Internet network. They provide many kinds of services, such as database services, other information searching services, telephone applications, video applications, networked games etc. The user initiates a service request by starting a desired application using the terminal user interface. In the mobile terminal, the execution environment is activated by the service request and also the requested application is activated. The terminal makes a connection via the mobile network to the Internet network or some other network where the desired service exists.
The requirements of different applications may differ significantly. Some applications require fast communication between sender and receiver. Such applications are, for example, video and telephone applications. Some other applications may require as error-free communication as possible, but the bit rate of the communication connection is less important. Such applications include e-mail and database applications.
Therefore, there is a problem in using these kinds of applications in mobile terminals, namely how to select the optimum bearer service for a particular communication task. In future mobile networks, it is likely that the service requirements of users will differ greatly, depending on the capabilities of the terminals they use, the applications they want to run, the capabilities of networks and the kind of user subscription they have.
In present systems, some applications contain information on what kind of bearer services they need. The bearer selection can be based on the destination server, which can be e.g. a so-called World Wide Web server (WWW) communicating with the Internet network. The selection of a bearer service is driven by the network address of the server being contacted and the network protocol being used.
Many mobile terminals communicate with networks using more than one bearer service. The network operator and/or user may wish to program the mobile terminal to use a specific bearer service in order to optimise a particular function, for example network loading, response times, etc.
At the present time the choice of a bearer service is typically driven by the application being used. The user or network operator may categorise applications by their use of bearer services.
These previously known systems all involve some inherent disadvantages. For example, some applications can be executed in different kinds of terminal where the properties of the terminal affect the demands on the bearer services of the applications being executed. Also, the user may have his/her own demands and preferences which are not taken into account in present systems. Furthermore, there may also be some situations in which the mobile network may not be able to provide all bearer services, for example when the network is overloaded.
In present systems, the mobile terminal and the mobile network negotiate the bearer service. If the network cannot provide the requested bearer service, probably the quality of service provided for the communication is not appropriate. Let us assume that there exists a video application where the resolution of the video is quite high, e.g. 800×640 pixels. If the user wishes to execute this video application with a mobile terminal which has means to connect via a high-speed circuit-switched data connection (HSCSD bearer service) and the mobile terminal is locally connected to a laptop PC which has a display with a resolution of at least the mentioned 800×640, the application may be executed with its default resolution. If the user only has a mobile terminal which comprises a lower resolution display, for example 640×480, the application will still try to request a bearer service for the maximum resolution (800×640), although a bearer service for smaller resolution (640×480) would be adequate.
There are also other criteria which affect the requirements of the bearer service needed. In another example, a mobile terminal can be used as a remote terminal for a server. The mobile terminal and the server need to exchange some data. The type of server for which the mobile terminal is used as a remote terminal may vary and so may the properties of the server. For example, the communication speed may differ. Therefore there can be different criteria for the selection of bearer service depending on properties of the server in question.
It is also possible that two mobile terminals are communicating with each other and must select bearer services. The selection of an appropriate bearer service depends inter alia on the properties of both mobile terminals and the properties of the mobile networks with which the mobile terminals are communicating.
The user may also visit the area of a mobile network other than his/her home mobile network. In the visited mobile network the bearer services that may be selected may vary from those of the home mobile network. The pricing policy may also differ.